What is the name of the API that allows external programs to access Wikipedia data?

The API that allows external programs to access Wikipedia data is the MediaWiki API.

It is the application-programming interface built into MediaWiki, the free wiki software that powers Wikipedia and other Wikimedia projects. Client programs can use it to retrieve page content, search articles, inspect revision histories, monitor recent changes, log in, and—where permitted—submit edits.

The API is accessed through an endpoint such as Wikipedia’s /w/api.php. Requests are sent over HTTP, and responses can be returned in formats including JSON and XML. This language-independent design lets tools written in different programming languages communicate with the same wiki.

A common mix-up is calling it simply a “REST API” or “Web API.” Those descriptions may be broadly understandable, but they are not the canonical product name. Tools such as Pywikibot, AutoWikiBrowser, and vandal-fighting software use the MediaWiki API behind the scenes. The API belongs to the MediaWiki platform, while Wikipedia is one prominent site that exposes it.